Mobile electronic apparatuses, such as cellular phones, PDAs (Personal Digital Assistants) and notebook personal computers (PCs), have rechargeable batteries. In a conventional cellular or mobile phone, applications consuming much power, such as music replay and video games, are frequently used in addition to major functions, such as genuine telephone functions of awaiting an incoming call and of making and receiving calls. Cellular phones are provided with a function to display or check on the amount of available remaining battery power, for power management of the cellular phones. When executing an application for music replay or game-playing on a cellular phone, a user should be careful of the remaining battery power, so that the incoming call awaiting and call making and receiving functions as the major functions of the cellular phone can be kept available.
A technology for accurately calculating the remaining battery capacity is available as “Impedance Track™” gas gauge technology from Texas Instruments.
Japanese Patent Application Publication JP 2000-253142-A published on Sep. 14, 2000 discloses power consumption reduction in a communication terminal device. In the communication terminal device, a remaining battery power is detected by a remaining battery power detecting unit, and a control unit compares the detected remaining battery power with a threshold value. If the control unit determines that the remaining power is lower than the threshold value, it disables supplementary functions, such as an incoming call indicator LED, a controller of incoming call indicating sound and a display, to thereby reduce power consumption. Thus the speech time or the incoming call awaiting time can be extended.
Japanese Patent Application Publication JP 2002-7002-A published on Jan. 11, 2002 discloses an electronic apparatus, which has a plurality of functions subject to power saving operation, and a power saving operation setting function to set priorities of such plural functions for the power saving operation.
Japanese Patent Application Publication JP 2002-199062-A (which corresponds to U.S. Patent Application Publication US 2002/0082059-A1) discloses a mobile terminal, which can reproduce data, such as music, stored therein. The mobile terminal is provided with battery charging state detecting means or remaining battery power detecting means, and allows starting of data reproduction when the start of charging the battery is detected, and prevents the data reproducing operation from being started when the remaining power of the battery is lower than a predetermined value. Thus, sound information is provided by desired music when the battery is in a charged state, and electric power can be saved when the remaining battery power is small.